If you look through the ten different sections of the Fifth Report on protection, issued by the British X-ray and Radium Protection Committee, you will find that few of these are really concerned with standards as normally understood by physicists. They are much more concerned with working conditions, for standards, even if they existed, could only be approached and not realised. With such things as lead equivalents, determined at considerable trouble by the National Physical Laboratory, there will be little discussion, for they are the result of measurements of precision. But if, sheltered behind these apparent standards of safety, the operator is careless in other working conditions, he will get no real security by giving lip service to a set of rules. One might almost say that if you accept the present standards of protection you may still be in danger, and if you neglect them you may get into trouble. We can only be as wise as we are at the time! The fact that the British X-ray and Radium Protection Committee has, since its inception twenty years ago, published no less than five different editions of its recommendations, means that not only has it tried to keep pace with the enlarging technical developments of the subject, but that it has tried to be a bit wiser with each edition. The Committee is busy at present on its sixth edition.